Merge tag 'libnvdimm-for-4.3' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm...

[cascardo/linux.git] / mm / Kconfig

diff --git a/mm/Kconfig b/mm/Kconfig
index d4e6495..3a4070f 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -648,3 +648,20 @@ config DEFERRED_STRUCT_PAGE_INIT
          when kswapd starts. This has a potential performance impact on
          processes running early in the lifetime of the systemm until kswapd
          finishes the initialisation.
+
+config ZONE_DEVICE
+       bool "Device memory (pmem, etc...) hotplug support" if EXPERT
+       default !ZONE_DMA
+       depends on !ZONE_DMA
+       depends on MEMORY_HOTPLUG
+       depends on MEMORY_HOTREMOVE
+       depends on X86_64 #arch_add_memory() comprehends device memory
+
+       help
+         Device memory hotplug support allows for establishing pmem,
+         or other device driver discovered memory regions, in the
+         memmap. This allows pfn_to_page() lookups of otherwise
+         "device-physical" addresses which is needed for using a DAX
+         mapping in an O_DIRECT operation, among other things.
+
+         If FS_DAX is enabled, then say Y.